The present invention relates generally to altitude-measuring devices, and more particularly to an apparatus for measuring and displaying the altitude of a kite when it is in the air.
People around the world have flown kites since time immemorial. Although kites have been occasionally used for meteorological and military use, the flying of kites is usually done by people of all ages for their pleasure and enjoyment. Kites, which vary widely in size and shape, commonly include a light frame typically made of strips of wood covered with paper or cloth. A long cord or string is attached to one end of the frame. The other end of the cord is wound on a bobbin, reel or the like which is held in the operator""s hand.
Kites are typically formed in the shape of a diamond or a box and one or more tails usually made of cloth is appended to one end of the kite for balancing purposes. When the kite is to be flown, the kite is released and the operator holding the reel in his or her hand runs along the ground until the kite begins to rise into the air. By pulling on the string the operator is able to maneuver the kite and to control the height or attitude to which it ascends.
In recent years, attempts have been made to design kites so as to increase the altitudes to which they are able to rise. As these heights have increased, as a result of these new designs, as well as through the use of new, lighter-weight materials in kite construction, so has the interest in measuring the altitude of a kite. For example, the person flying a kite may be interested in knowing how high the kite has risen both as a matter of intellectual curiosity and as an indication of the quality of the kite and, particularly in kite-flying competitions, of his or her skill in kite flying.
The task of determining the altitude attained by a kite is complicated by the fact that a kite rarely if ever rises vertically from the ground, but rather extends upwards at some acute angle with respect to the horizontal. Thus merely measuring the length of string unwound from the reel as the kite rises to its current position would not provide an indication of the altitude of the kite. There thus exists a need for an apparatus that is able to reliably measure the height or altitude of a kite on a continuing, real-time basis with an apparatus which is economical, light in weight and convenient to use.
The kite altitude-measuring apparatus of the present invention measures the length of line unwound from the reel as well as the angle that the line and thus the kite makes with respect to the horizontal (or vertical). In accordance with the invention, the line is passed through a pivotable member that moves along an arcuate path with respect to a stationary angle sensor. The latter is effective to address a memory containing address locations in which the sines of the angles along the arcuate path through which the pivotable member moves so as to provide the appropriate angle sine data to a microprocessor. The sine of the measured angle of the pivotable member and thus of the kite itself is multiplied in the microprocessor by the measured length of the paid out line to develop a signal that represents the altitude of the kite.
In an embodiment of the invention herein disclosed, the kite line passes through the interior of a pivotable tubular member, which, in accordance with the number of axially spaced conductive segments on the line that pass therethrough, produces an electrical signal that represents the length of the line unwound from the reel as the kite rises to its current position. The tubular member is mounted so that it can pivot about an axis to the angle made by the paid out line with respect to the horizontal.
In another aspect of the invention, a plurality of angularly spaced contacts mounted on the angle sensor are positioned near the end of the pivotable tubular member such that a contact at one end of the tubular member makes contact with one of the spaced contacts on the angle sensor in accordance with the angular orientation of the tubular member and thus of the kite. Each of the spaced contacts may be, as herein disclosed, associated uniquely with an address in the memory that stores the sine of the angle associated with that contact and thus with the angle of the tubular member with which it is then in contact.